Up to now, to produce a woody formed article in which woody material such as wood powder and the like and thermoplastic resin are mixed, a method consisting of melting said thermoplastic resin by employing such as an extruder, heating and melting type kneader, and the like, adding woody material such as wood powder to said melted thermoplastic resin to mix, and forming the resulting mixture into a formed article by extrusion molding or a method consisting of hot-pressing a mixture of said woody material and chip or pellet of said thermoplastic resin has been provided. As said woody material, fine woody material such as crushed waste paper have been used besides said wood powder. The resulting woody formed article is useful as building boards and material for furniture.
In a case where said woody material is added to said melted thermoplastic resin at a high temperature and pressure as described above, many kinds of sugar, lignin and the like originally contained in said woody material come out in said melted thermoplastic resin and further said components coming out from said woody material are dispersed wholly in said melted thermoplastic resin by kneading action of the screw of an extruder and the like under a high pressure. As a result, a problem that said thermoplastic resin is degraded by said components has arisen, and in the case where said thermoplastic resin is degraded, desirable hardness and strength of the resulting formed article can not be ensured, and the resulting formed article has poor toughness to be brittle and further has poor weather resistance, causing chalking by being exposed to ultraviolet rays outdoors.
Further in a case where said thermoplastic resin chip or pellet is mixed in said woody material, it is difficult to mix uniformly said woody material and said thermoplastic resin under room temperature and in a case where crushed waste paper is used as a woody material, a light woody formed article which can be used in place of plywood, OSB, and the like which use thermosetting resin and have excellent strength is difficult to obtain since said crushed waste paper has a big specific surface area so that a big amount of thermoplastic resin as a binder is necessary and as a result the density of the resulting formed article becomes high.